package com.concurrent.test2;

import java.text.SimpleDateFormat;
import java.util.Random;

public class Test40 extends Thread{
        // SimpleDateFormat 不是线程安全的，所以每个线程都要有自己独立的副本
        private static final ThreadLocal<SimpleDateFormat> formatter = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyyMMdd HHmm"));

        public static void main(String[] args) throws InterruptedException {
            Test40 obj = new Test40();
            for(int i=0 ; i<10; i++){
                Thread t = new Thread(obj, ""+i);
                Thread.sleep(new Random().nextInt(1000));
                t.start();
            }
        }

        @Override
        public void run() {
            System.out.println("Thread Name= "+Thread.currentThread().getName()+" default Formatter = "+formatter.get().toPattern());
            try {
                Thread.sleep(new Random().nextInt(1000));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            //formatter pattern is changed here by thread, but it won't reflect to other threads
            formatter.set(new SimpleDateFormat());

            System.out.println("Thread Name= "+Thread.currentThread().getName()+" formatter = "+formatter.get().toPattern());
        }


}
